The Lacrimal Bone
The lacrimal bone (Latin “lacrima” = tears) is the smallest bone of the skull (avg. 11-14 mm). It is paired and sits inside the bony orbit taking up a small area of the most anterior part of the medial wall.
One differentiates between the lateral (orbital) and medial (nasal) surface. The lateral surface features the lacrimal groove which forms the fossa for lacrimal sac together with the lacrimal groove of maxilla. The lacrimal sac and the naso-lacrimal duct lie within this depression. Posteriorly the fossa is limited by the posterior lacrimal crest. The medial surface contributes to the middle nasal meatus and comes in contact with the ethmoid cells.
The lacrimal bone has a common border with the frontal process of the maxilla anteriorly. This incomplete articulation does not weaken their union as the fossa is very small and both bones are tightly bordered by many others. Superiorly the bone articulates with the frontal bone. Posteriorly it borders with the lamina papyracea of the anterior ethmoid cells, sometimes even constituting part of their walls. Inferiorly the bone extends to the nasal cavity to articulate with the anterior part of the inferior nasal concha.
During embryological development the lacrimal bone has one ossification center arising from the cartilaginous nasal capsule. It matures through intramembranous ossification. In newborns they are already well developed and completely ossified.